Small intestinal neoplasms.
Small intestinal neoplasms are uncommonly encountered in clinical practice. They may occur sporadically, in association with genetic diseases (e.g., familial adenomatous polyposis coli or Peutz-Jeghers syndrome), or in association with chronic intestinal inflammatory disorders (e.g., Crohn's disease or celiac sprue). Benign small intestinal tumors (e.g., leiomyoma, lipoma, hamartoma, or desmoid tumor) usually are asymptomatic but may present with intussusception. Primary malignancies of the small intestine-including adenocarcinoma, leiomyosarcoma, carcinoid, and lymphoma-may present with intestinal obstruction, jaundice, bleeding, or pain. Extraintestinal neoplasms may involve the intestine via contiguous spread or peritoneal metastasis. Hematogenous metastases to the intestine from an extraintestinal primary are unusual and are most typical of melanoma. Because the small intestine is relatively inaccessible to routine endoscopy, diagnosis of small intestinal neoplasms is often delayed for months after onset of symptoms. When the diagnosis is suspected, enteroclysis is the most useful imaging study. Small bowel endoscopy (enteroscopy) is increasingly widely available and may permit earlier, nonoperative diagnosis.